DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 137 
my first impression. I may further say that of very many skeletons, in various stages 
of growth, examined by me in Continental and English Museums, none exhibited more 
than six cervicals. 
As to the second point, recognition of the absent one, De Blainville took up the 
question very categorically, inasmuch as he maintained that in one of the Leyden speci- 
mens he counted seven; and he assumes rather than proves that “la sixiéme, finit par 
disparaitre dans son corps; l’are restant libre dans les chairs, est enleyé avec elles.” 
This statement has been contradicted by Vrolik, who cites Temminck, Schlegel, and 
Peters as witnesses in evidence of its absence in the Leyden skeleton in question. In 
my examination of the same specimen I certainly only found six. Professor Brandt also 
throws doubts on De Blainville’s assertion ; and he himself, in a study of the Sirenian 
neck-vertebre, holds, from analogy in the disposition of the cervicals of Halicore and 
Rhytina, and the way in which the head of the first rib articulates, that the seventh is 
that which is wanting. The first dorsal, however, or numerically the seventh from the 
cranium, he is inclined to regard in the light of an anomaly—functionally a dorsal, yet 
in some way a cervical. Somewhat incongruously I think, while admitting on sound 
grounds but six for the neck, he would do away with this apparent exception by the less 
stable assumption of a cervical simulating an undoubted true dorsal. Professor F lower, 
in a short communication’, very sensibly argues against Brandt’s opinion. Basing his 
reasoning on the cervical irregularity extant in the Sloth, as elucidated by Bell and 
Turner, and on the individual characters of the seven cervical vertebree of the Dugong 
compared with those of the Manatee, he concludes that morphologically the sixth is 
the missing one in the latter animal. 
For my own part I venture to dissent from the above distinguished authorities; and 
suggest that it is the usual third cervical of Mammals which is the undeveloped or 
absent one in Manatus. This conviction I am led to adopt for several reasons. In 
Cetacea with ankylosed cervicals more generally the third is the least distinct, the 
fourth, fifth, and sixth by degrees evincing greater separation. In adult Sirenia 
occasionally the axis and so-called third and fourth are found partially united. In 
them also the three vertebrae succeeding the axis, although subequal in thickness, do 
show slight successive increment, so that, ceteris paribus, the missing true third one 
would be most reduced, and its thinned body and lamina more readily coalesced to non- 
detection with the enlarged axis. Again, in my dissections (vide fig. 29) I found that 
there is a tiny accessory tendon of the scalenus muscle, which comes from a small 
triangular fleshy slip alongside of the larger axial division, and is fixed immediately 
hehind it to the same vertebra. The third nerve passes between them. This diminutive 
additional tendon, therefore, completes the normal number seven of the cervical attach- 
ments of the scalenus, notwithstanding there being only six well-developed neck-ver- 
tebre ; moreover its relation to the third nerve is, I hold, important. Inferentially this 
* Nat. Hist. Rev. 1864, p. 259, 
y2 
